In regions where sub-freezing temperatures persist for prolonged periods of time sufficient to cause the ground to become frozen, water supply systems for mobile homes, stock tank waterers and the like are subject to freezing of water in the riser pipe connected between the mobile home or stock tank waterer and the underground water supply pipe located below the frost line.
If the water in the riser pipe freezes, it blocks the pipe, interrupting the flow of water, and often bursts the pipe. This problem is especially severe when water is supplied intermittently or stands in the riser pipe for long periods of time.
A solution to this problem is given in applicant's U.S. Pat. No. 3,120,600 in which the riser pipe is wrapped with a heat tape covered with insulation and located within an outer pipe. The riser pipe with the surrounding heat tape encased in the outer pipe is prefabricated as a unit and then is utilized in place of the conventional riser pipe for use in mobile home or stock tank waterer installations.
While the prefabricated units of this earlier patent have given satisfactory service in a large number of installations, it is necessary to remove the top cap and valve assembly to replace the heat unit if the heat unit should ever fail. This means that the water supply must be turned off if it ever does become necessary to replace a heat unit.
In the installation of the prefabricated riser pipe assemblies for a mobile home court or the like, it is necessary to install and connect the riser pipe assemblies prior to the time that any of the mobile homes are moved into place for service by the individual riser pipe systems. Since the mobile homes are not moved into place until some subsequent time, no rentals or sales are effective until later. Thus, it is desirable to reduce the initial cost of the water supply system as much as possible.